ICSE Living Science Chemistry for Class 7 Solutions Chapter 4 Chemistry in Everyday Life
Check Your Progress
Question 1.
Name the metal that exists in the liquid state at room temperature.
Answer:
Mercury
Question 2.
Name the metal that is used for galvanizing iron.
Answer:
Zinc
Question 3.
Which non-metal is a good conductor of electricity ?
Answer:
Graphite (form of carbon)
Question 4.
Which non-metal is used for bleaching cotton and jute fabric ?
Answer:
Chlorine
Question 5.
Which alloy is used to join electrical and electronic circuits ?
Answer:
Solder
A. Tick the most appropriate answer.
Question 1.
This non-metal is a liquid at room temperature,
a. Fluorine
b. Chlorine
c. Bromine
d. Iodine
Answer:
c. Bromine
Question 2.
The metal which is always present in an amalgam is
a. iron
b. aluminium
c. mercury
d. magnesium
Answer:
c. mercury
Question 3.
During galvanization, iron metal is coated with a thin coating of this metal.
a. Chromium
b. Tin
c. Zinc
Answer:
c. Zinc
Question 4.
Brass is an alloy of
a. copper and zinc
b. copper and tin
c. lead and tin
d. iron and zinc
Answer:
a. copper and zinc
Question 5.
Which of the following alloys contains a non-metal as one of the constituents ?
a. Brass
b. Duralumin
c. Steel
d. Bronze
Answer:
c. Steel
Question 6.
A powdered mixture of limestone, clay and gypsum is called
a. plastic
b. glass
c. cement
d. fertilizer
Answer:
c. cement
Question 7.
Important ingredients for making glass are
a. limestone, sodium hydroxide and sand
b. limestone and sand
c. limestone, soda ash and sand
d. lime and soda ash.
Answer:
c. limestone, soda ash and sand
Question 8.
Carbon fibres consist of a long chain of
a. carbon atoms
b. oxygen
c. nitrogen
d. hydrogen
Answer:
a. carbon atoms
Question 9.
Which of the following is used to make non-stick cookware ?
a. PVC
b. Polystyrene
c. Polyethylene
d. Silicone
Answer:
d. Silicone
Fill in the blanks.
Question 1.
………….. is the most abundant metal found in the earth’s crust.
Answer:
Aluminium is the most abundant metal found in the earth’s crust.
Question 2.
…………… is the best conductor of heat and electricity.
Answer:
Silver is the best conductor of heat and electricity.
Question 3.
The process of depositing a thin layer of zinc on the surface of iron articles is called …………
Answer:
The process of depositing a thin layer of zinc on the surface of iron articles is called galvanization.
Question 4.
The deficiency of …………… in the diet causes goitre.
Answer:
The deficiency of iodine in the diet causes goitre.
Question 5.
……………. is used to purify drinking water.
Answer:
Chlorine is used to purify drinking water.
Question 6.
…………… is used to fill electric bulbs and tubes.
Answer:
Argon is used to fill electric bulbs and tubes.
Question 7.
………….. is an alloy of copper, zinc and tin.
Answer:
Bronze is an alloy of copper, zinc and tin.
Question 8.
Man-made chemicals used to kill pests are called
Answer:
Man-made chemicals used to kill pests are called pesticides.
Question 9.
…………… is better than soap for washing clothes when the water is hard.
Answer:
Detergent is better than soap for washing clothes when the water is hard.
Question 10.
Drugs that relieve pain are known as …………
Answer:
Drugs that relieve pain are known as analgesics.
Question 11.
Penicillin was discovered by ………….
Answer:
Penicillin was discovered by Alexander Flemming.
Question 12.
……………. glass is used to make sun shields and sunglases.
Answer:
Photochromatic glass is used to make sun shields and sunglases.
C. State if the following statements are true or false. Correct the statement if it is. false.
Question 1.
The most abundant non-metal in the earth’s crust is silicon.
Answer:
False. The most abundant non-metal in the earth’s crust is oxygen.
Question 2.
Diamond is a poor conductor of electricity.
Answer:
True
Question 3.
Duralumin is an alloy of copper and tin.
Answer:
False. Duralumin is an alloy of copper, aluminium, magnesium and manganese.
Question 4.
The non-metallic component present in stainless steel is phosphorus.
Answer:
False. The non-metallic component present in stainless steel is carbon.
Question 5.
Solder is an alloy consisting of lead and tin.
Answer:
True
Question 6.
Glass is also called a supercooled liquid.
Answer:
Tme
Question 7.
Optical fibres are used for making components of aircraft.
Answer:
False. Carbon fibres are used for making components of aircraft.
Question 8.
Silicones are used as non-stick coatings in utensils.
Answer:
Tme
D. Name the following.
Question 1.
The property by virtue of which metals can be beaten into thin sheets.
Answer:
Malleability
Question 2.
The property by virtue of which metals can be drawn into thin wires without breaking.
Answer:
Ductility
Question 3.
A mixture of one metal with other metals or non-metals.
Answer:
Alloy
Question 4.
The alloy that is light, hard, strong, corrosion-resistant and is used in making bodies of aircraft
Answer:
Duralumin
Question 5.
Chemical substances that provide essential nutrients to plants for their growth.
Answer:
Fertilizers
Question 6.
Chemials that are used to kill pests.
Answer:
Pesticides
E. Match The Following
| Column A | Column B |
| 1. Limestone | a. steel making |
| 2. Lead | b. germicide |
| 3. Brass | c. galvanizing |
| 4. Blue vitriol | d. protective shield around nuclear reactors |
| 5. Zinc | e. electrical fittings |
| 6. Silver | f. pigment in paints |
| 7. Zinc oxide | g. dentistry |
| 8. Plaster of Paris | h. calcium carbonate |
| 9. Pyrex glass | i.laboratory equipment |
| j. calcium sulphate hemihydrate |
Answer:
| Column A | Column B |
| 1. Limestone | h. calcium carbonate |
| 2. Lead | d. protective shield around nuclear reactors |
| 3. Brass | e.electrical fittings |
| 4. Blue vitriol | b. germicideb. calcium hydroxide solution |
| 5. Zinc | c. galvanizing g. dentistry |
| 6. Silver | g. dentistry |
| 7. Zinc oxide | f. pigment in paints |
| 8. Plaster of Paris | j. calcium sulphate hemihydrate |
| 9. Pyrex glass | i.laboratory equipment |
F. Answer the following in short.
Question 1.
Which property of copper metal is utilized in making copper wires ?
Answer:
Copper is a .very good conductor of electricity.
Question 2.
Name a metal used for making electrodes and electrolytic cells.
Answer:
Platinum
Question 3.
Which is the most used and cheapest metal ?
Answer:
Iron
Question 4.
Why does silver jewellery turn dark when used ?
Answer:
Silver darkens as it reacts with oxygen and sulphur compounds in the air.
Question 5.
Which property of graphite is used for making electrodes?
Answer:
Graphite is a good conductor of electricity.
Question 6.
Name the alloy used to make the body of aircraft.
Answer:
Duralumin
Question 7.
Name the acid used to prepare silver chloride.
Answer:
Hydrochloric acid (HCl)
Question 8.
What is an amalgam ? Give an example.
Answer:
An alloy of mercury with one or more metals is called an amalgam (liquid alloy). Example : a mixture of silver and mercury which is used in dentistry for filling tooth cavities.
Question 9.
What is the role of limestone in the extraction of iron?
Answer:
Limestone is used to remove impurities in the extraction of iron.
Question 10.
Which compund is used in hospitals for plastering fractured bones ?
Answer:
Plaster of Paris/Calcium sulphate hemihydrate (CaSO4 \(\frac {1}{2}\)H2O)
Question 11.
What are antihistamines ?
Answer:
Antihistamines are medicines used to treat allergies such as skin rashes, sneezing, etc.They are also called anti-allergic drugs. Examples : diphenhydramine (Benadiyl) and pheniramine maleate (Avil).
Question 12.
Why is glass called a supercooled liquid ?
Answer:
Glass is made by cooling molten ingredients such as silica or sand. Hence, it is also called a supercooled liquid.
G Write the chemical formulae of the following.
Question 1.
1. Limestone
2. Blue vitriol
3. Gypsum
4. Plaster of Paris
5. Silicon carbide
6. Urea
Answer:
1. Limestone – CaCO3 (calcium carbonate)
2. Blue vitriol – CuSO2.5H2O (hydrated copper sulphate)
3. Gypsum – CaSO4.H2O (hydrated calcium sulphate)
4. Plaster of Paris – CaSO4. H2O) (calcium sulphate hemihydrate)
5. Silicon carbide – SiC
6. Urea – NH2CONH2
H. Name the constituents of the following.
1. Brass
2. Bronze
Duralumin
4. Steel
5. Solder
6. German silver
Answer:
1. Brass – Brass is composed of copper (60 to 80%) and zinc (20 to 40%).
2. Bronze – Bronze is composed of copper (80%), zinc (1%) and tin (19%).
3. Duralumin – Duralumin is compound of aluminium (95%), copper (4%), magnesium (0.5%) and manganese (0.5%)
4. Steel – Steel is composed of iron (98.5 to 99%) and carbon (0.1 and 0.5%)
5. Solder – Solder is composed of lead (50%) and tin (50%)
6. German silver – German silver is composed of copper (50%), zinc (30%) and nickel (20%).
I. Answer the following in detail.
Question 1.
Give difference between metals and non-metals with reference to the following.
a. Conductivity of heat and electricity
b. Lustre
c. Malleability
d. Ductility
Answer:
a. Conductivity of heat and electricity – Metals are good conductors of heat and electricity.
Example : silver, copper, etc.
Non-metals are bad conductors of heat and electricity, except graphite.
b. Lustre – Metals are lustrous, i.e. have shiny surface.
Examples : silver and gold.
Non-metals are non-lustrous. They have dull surface except graphite.
c. Malleability – Metals are malleable, so can be beaten into sheets.
Examples : iron, tin, etc.
Non-metals are non-malleable and are brittle.
d. Ductility – Metals are ductile, so can be drawn into wires without breaking.
Examples : aluminium, copper, etc.
Non-metals are not ductile.
Question 2.
Define and give one example of each :
a. Antipyretics
b. Analgesics
c. Antibiotics
d. Antiseptics
Answer:
a. Antipyretics – Antipyretics are medicines used to control fever. Examples are aspirin, paracetamol and analgin.
b. Analgesics – Analgesics are medicines used for getting relief from pain. Examples,are naproxen ibuprofen and aspirin.
c. Antibiotics – Antibiotics are chemical substances produced by microorganisms (bacteria, fungi and moulds) and can prevent the growth of or destroy other microorganisms. Examples are penicillin, streptomycin, tetracycline.
d. Antiseptics – Antiseptics are chemicals that kill or prevent the growth of infectious microorganisms. It can be applied on cuts and wounds. Examples are boric acid and hydrogen peroxide.
Question 3.
What is reinforced concrete ? State one application of reinforced concrete.
Answer:
Reinforced concrete is concrete in which steel rods, bars or mesh are embedded in mixture of cement, sand, gravel or chips (crushed stones) and water. Roffs, columns and beams in buildings, bridges and dams are made from reinforced concrete.
Question 4.
Write the properties of the following types of plastics :
a. Polythene
b. PVC
c. PTFE
d. Bakelite
Answer:
a. Polythene – Properties of polythene : Strong, flexible and water resistant ; can be rolled into sheets or moulded into any shape.
b. PVC – Properties of PVC (polyvinyl chloride) Tougher than polythene, bad conductor of heat and electricity.
c. PTFE – Properties of PTFE (poly tetrafluroethylene) or TEFLON Heat and chemical resistant, slippery.
d. Bakelite – Properties of Bakelite Bad conductor of heat and electricity, very hard.
Question 5.
Compare between carbon fibres and optical fibres.
Answer:
Carbon fibres consist of a long chain of carbon atoms. They are stronger than steel and possess a very high tensile strength even at higher temperatures. They are also corrosion resistant. They are used for making components of aircrafts, body of autombiles, sports goods like shoes and tennis racquets, artificial implants for the body, etc.
Optical fibres are fine thread-like tubes made of glass. They can carry information coded in light or infrared signals. It is used in tele-communication, in performing surgery of internal organs without cutting open the body.
Question 6.
State one use of the following.
a. Soft glass
b. Hard glass
c. Flint glass
d. Lead crystal glass
Answer:
a. Use of soft glass or soda glass. It is used in making glass tubes, window panes, bottles and common glassware.
b. Use of hard glass or potash glass. It is used for making hard glass apparatus.
c. Use of flint glass : It is used for making electric bulbs and optical instruments.
d. Use of lead crystal glass : It is used to make optical parts, high quality and expensive glass ornaments.
J. Give reasons for the following.
Question 1.
In hospitals, human body tissues and blood are stored in liquid nitrogen.
Answer:
Liquid nitrogen is used to store human body tissues and blood in hospitals as it provides a very low temperature, (liquid nitrogen is nitrogen in a liquid state at an extremely low temperature).
Question 2.
Duralumin is used for making bodies of aeroplanes.
Answer:
Because duralumin is light, hard, strong and corrosion resistant
Question 3.
Which one should you use for washing-soap or detergent?
Answer:
Detergents should be used for washing as they have better cleaning action than soaps and form lather even in hard water.
Living Science Chemistry Class 7 ICSE Solutions